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Re: [EFM] RE: [EFM-Copper] the merits of 12 kft and +


ISDN NTs in Germany shall normally be powered locally at the
customer's premises. The ISDN S0 bus is then able to feed
terminals up to 4.5 W in total. If no local powering is
available the NT is fed remotely from the CO battery. The
power delivered to terminals on the S0 bus is then limited to
0.5 W. Only one terminal per bus is allowed to operate in this
situation ("emergency phone"). Failure of local powering is
indicated by reversing the supply voltage on the bus. All
terminals not provisioned for emergency mode disconnect

I do not know how many customers are actually able to use
this emergency powering. A lot of people in Germany own a
small ISDN PABX, often based on the European DECT standard
(cordless telephone), which certainly needs more than 0.5 W
to operate. Personally, I have an ISDN telephone set at home
which operates in emergency mode although some features are
then disbaled (LCD display switched off, integrated phone book
not available etc.).

On the other hand, when local power is available the PABX
itself feeds the terminals and the ISDN NT is not required to
feed the S0 bus. Customers with a PABX therefore often
disconnect the ISDN NT from the local power and rely on the
remote powering from the CO.


Thomas M. Bossmeyer             Mint Technology            +-----+
Senior Systems Engineer         LSI Logic GmbH          LSI|LOGIC|
Phone: +49 711 139 69-23        Ingersheimer Str. 20       |     |
Fax:   +49 711 866 14 28        70499 Stuttgart            +-----+
mailto:bossm@xxxxxxxx           Germany
tel;fax:+49 711 8661428
tel;work:+49 711 13969-23
org:LSI Logic;Mint Technology
adr:;;Ingersheimer Str. 20;Stuttgart;;70825;Germany
title:Senior Systems Engineer
fn:Thomas Bossmeyer